power surge

ok ive nearly got it working properly now but for some reason even though ive added a power adapter to the sound card, when i connect it to the computer through the usb port i get a bubble popping up on my PC saying power surge on usb port. if i load the software i can still get it to configure and the left hand deck works perfectly. for some reason though, the right hand channel has feed back and is distorting the mp3 files being played at the time. i need more power but have no idea how to achieve it!